The present invention relates to a residual pressure valve device as well as to a valve and a gas cylinder comprising such a device.
Residual pressure valve devices are provided to avoid a pressurized gas cylinder being totally drained. Said devices are general arranged upstream of a pressure regulator (upstream in the sense of gas withdrawal).
However, such devices create load losses on the gas tapping circuit. Known devices generate a load loss equal to the pressure setting of the residual pressure valve. As a result, taking into consideration the characteristics of the pressure regulator downstream (flow rate/pressure), the tapping flow rate can only be supplied up to the pressure setting of the residual pressure valve but said flow rate drops rapidly when approaching the pressure setting of the valve. For example, for a residual pressure valve device preset to 20 bar, the tapping rate and the outlet pressure of a regulator downstream drop from 35 to 40 bar.
In addition, when a shut-off valve upstream of such a device is opened, the inlet of a high-pressure gas flow can generate a phenomenon called a “water hammer”, that is to say an overpressure due to a sudden variation in the pressure and speed of the gas.